Methods and systems for diagnosing a turbocharger

ABSTRACT

Various methods and systems are provided for a turbocharger. In one example, a method includes receiving a signal indicative of a monitored pressure of a pressurized oil supply of a turbocharger or other turbomachine. The method further includes determining whether a high frequency component of the signal meets one or more designated criteria, and, if the high frequency component of the pressure meets the one or more designated criteria, generating a first control signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/553,896, filed Oct. 31, 2011 and is acontinuation-in-part of U.S. patent application Ser. No. 13/234,517filed Sep. 16, 2011, the disclosures of each of which are incorporatedby reference in their entirety for all purposes.

FIELD

Embodiments of the subject matter herein relate to internal combustionengine systems. Other embodiments relate to turbochargers.

BACKGROUND

Turbochargers may be used in an engine system to increase a pressure ofair supplied to the engine for combustion. In one example, theturbocharger includes a turbine coupled in an exhaust passage of theengine which at least partially drives a compressor via a shaft toincrease the intake air pressure. Many turbochargers use journalbearings to support the rotating shaft. These bearings are lubricatedwith a pressurized oil supply that is regulated to a relatively constantpressure through the use of a control valve or an orifice. Often, thesteady oil pressure is monitored by a pressure transducer and a controlsystem to assure the machine is properly lubricated and cooled.

Over time, the shaft and/or journal bearings or related components maybe subject to wear. Eventually, the journal bearings may fail, forexample. Often, because of this, the life of the turbocharger is shorterthan the rest of the engine. Also, due to the high level of energystored in the turbocharger, its failure is usually catastrophic. Thisresults in the unexpected shutdown of the engine, which can have safetyand cost consequences to an operator of the system.

BRIEF DESCRIPTION

Thus, in one embodiment, a method includes receiving a signal indicativeof a monitored pressure of a pressurized oil supply of a turbocharger orother turbomachine. The method further includes determining whether ahigh frequency component of the signal meets one or more designatedcriteria. If the high frequency component of the pressure meets the oneor more designated criteria, first control signal is generated. Forexample, the control signal may initiate an operator alert relating to apredicted health (or other operational state) of the turbocharger.

The predicted health of the turbocharger may indicate degradation of theturbocharger. As an example, when a bearing clearance of theturbocharger shaft increases due to wear, the turbocharger shaft maybecome unbalanced, thereby generating or increasing a frequency of thehigh frequency component of the signal. By monitoring the high frequencycomponent of the signal, bearing health may be monitored and appropriateactions may be taken to adjust the operation of the turbocharger and/orprovide service to the turbocharger to prevent an unexpected failure,for example.

It should be understood that the brief description above is provided tointroduce in simplified form a selection of concepts that are furtherdescribed in the detailed description. It is not meant to identify keyor essential features of the claimed subject matter, the scope of whichis defined uniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 shows a schematic diagram of a vehicle with a turbocharger.

FIG. 2 shows a cross-sectional view of a portion of a turbocharger.

FIG. 3 shows a flow chart illustrating a method for diagnosing aturbocharger based on pressure measurements.

FIG. 4 shows a flow chart illustrating a method for diagnosing aturbocharger using frequency content of a pressure signal.

FIG. 5 shows a graph of frequency content of a pressure signal.

FIG. 6 shows a flow chart illustrating a method for diagnosing aturbocharger based on a pressure measurement.

FIG. 7 shows a cross-sectional view of a portion of a turbocharger.

FIG. 8 shows a graph of a pressure versus time signal analysis.

FIG. 9 shows a flow chart illustrating a method for diagnosing aturbocharger based on a pressure measurement in an oil supply cavity ofthe turbocharger.

DETAILED DESCRIPTION

The following description relates to various embodiments of methods andsystems for diagnosing a turbocharger. One example method comprisesreceiving a signal indicative of a monitored pressure of a pressurizedoil supply of a turbocharger or other turbomachine. The method furthercomprises determining whether a high frequency component of the signalmeets one or more designated criteria, and, if the high frequencycomponent of the pressure meets the one or more designated criteria,generating a first control signal. In some embodiments, the methodfurther comprises determining whether a magnitude of change in thebaseline component of the signal is more than a threshold amount. If thebaseline component is changing more than the threshold amount, a secondcontrol signal is generated. The first and second control signals mayindicated degradation of the turbocharger. For example, as a result ofwear, the bearing clearance may increase and the turbocharger shaft maybecome unbalanced. As such, the high frequency component of the signalmay increase, for example, and the baseline component of the signal maydecrease. Thus, by monitoring the high frequency and baseline componentsof the pressure signal, degradation of the turbocharger may bedetermined, as will be described in greater detail below.

In one embodiment, the turbocharger may be coupled to an engine in avehicle. A locomotive system is used to exemplify one of the types ofvehicles having engines to which a turbocharger, or multi-turbocharger,may be attached. Other types of vehicles may include on-highwayvehicles, and other off-highway vehicles such as mining equipment andmarine vessels. Other embodiments of the invention may be used forturbochargers that are coupled to stationary engines. The engine may bea diesel engine, or may combust another fuel or combination of fuels.Such alternative fuels may include gasoline, kerosene, biodiesel,natural gas, and ethanol. Suitable engines may use compression ignitionand/or spark ignition.

FIG. 1 shows a block diagram of an example embodiment of a vehiclesystem 100, herein depicted as a rail vehicle 106 (e.g., locomotive),configured to run on a rail 102 via a plurality of wheels 112. Asdepicted, the rail vehicle 106 includes an engine system with an engine104, such as an internal combustion engine.

The engine 104 receives intake air for combustion from an intake passage114. The intake passage 114 receives ambient air from an air filter (notshown) that filters air from outside of the rail vehicle 106. Exhaustgas resulting from combustion in the engine 104 is supplied to anexhaust passage 116. Exhaust gas flows through the exhaust passage 116,and out of an exhaust stack of the rail vehicle 106.

The engine system includes a turbocharger 120 (“TURBO”) that is arrangedbetween the intake passage 114 and the exhaust passage 116. Theturbocharger 120 increases air charge of ambient air drawn into theintake passage 114 in order to provide greater charge density duringcombustion to increase power output and/or engine-operating efficiency.The turbocharger 120 may include a compressor (not shown in FIG. 1)which is at least partially driven by a turbine (not shown in FIG. 1).While in this case a single turbocharger is shown, the system mayinclude multiple turbine and/or compressor stages. The turbocharger isdescribed in greater detail below with reference to FIG. 2.

In some embodiments, the vehicle system 100 may further include anexhaust gas treatment system coupled in the exhaust passage upstream ordownstream of the turbocharger 120. In one example embodiment, theexhaust gas treatment system may include a diesel oxidation catalyst(DOC) and a diesel particulate filter (DPF). In other embodiments, theexhaust gas treatment system may additionally or alternatively includeone or more emission control devices. Such emission control devices mayinclude a selective catalytic reduction (SCR) catalyst, three-waycatalyst, NO_(x) trap, or various other devices or systems.

The rail vehicle 106 further includes a controller 148 to controlvarious components related to the vehicle system 100. In one example,the controller 148 includes a computer control system. The controller148 further includes computer readable storage media (not shown)including code for enabling on-board monitoring and control of railvehicle operation. The controller 148, while overseeing control andmanagement of the vehicle system 100, may be configured to receivesignals from a variety of engine sensors 150, as further elaboratedherein, in order to determine operating parameters and operatingconditions, and correspondingly adjust various engine actuators 152 tocontrol operation of the rail vehicle 106. For example, the controller148 may receive signals from various engine sensors 150 including, butnot limited to, engine speed, engine load, boost pressure, exhaustpressure, ambient pressure, exhaust temperature, intake manifold airpressure (MAP) 154, etc. Correspondingly, the controller 148 may controlthe vehicle system 100 by sending commands to various components such astraction motors, alternator, cylinder valves, throttle, etc. In oneexample, the controller 148 may shut down the engine in response to anengine crankcase pressure greater than a threshold pressure.

In one embodiment, as described below with reference to FIG. 3, thecontroller 148 may be configured to receive signals indicating pressurefrom a plurality of pressure sensors positioned in various locationswithin the turbocharger, e.g., first and second different locations. Asan example, a first pressure sensor which outputs a first pressuresignal may be positioned in a seal cavity of the turbocharger and asecond pressure sensor which outputs a second pressure signal may bepositioned in an oil cavity of the turbocharger. The controller mayidentify degradation of the turbocharger responsive to a differencebetween the first pressure and the second pressure greater than athreshold difference.

FIG. 2 shows a view of an example embodiment of a turbocharger 200 thatmay be coupled to an engine, such as turbocharger 120 described abovewith reference to FIG. 1. The view shown in FIG. 2 is a cross-sectionalview of a portion of the turbocharger 200. In one example, turbocharger200 may be bolted to the engine. In another example, the turbocharger200 may be coupled between the exhaust passage and the intake passage ofthe engine. In other examples, the turbocharger may be coupled to theengine by another suitable manner.

The turbocharger 200 includes a turbine 202 and a compressor 204.Exhaust gases from the engine pass through the turbine 202, and energyfrom the exhaust gases is converted into rotational kinetic energy torotate a shaft 206 which, in turn, drives the compressor 204. Ambientintake air is compressed (e.g., pressure of the air is increased) as itis drawn through the rotating compressor 204 such that a greater mass ofair may be delivered to the cylinders of the engine.

In some embodiments, the turbine 202 and the compressor 204 may haveseparate casings which are bolted together, for example, such that asingle unit (e.g., turbocharger 200) is formed. As an example, theturbine may have a casing made of cast iron and the compressor may havea casing made of an aluminum alloy. In other examples, casings of theturbine and the compressor may be made of the same material. It shouldbe understood the turbine casing and the compressor casing may be madeof any suitable materials.

As depicted in FIG. 2, a first pressure sensor 232 is positioned at adiffuser 228 in the compressor casing to measure a pressure in thecompressor casing. The diffuser 228 is a divergent duct in thecompressor casing which converts velocity energy to pressure energy, forexample. The pressure sensor 232 may be a transducer, for example, whichgenerates a signal as a function of the pressure imposed. The pressureat the diffuser 228 may be substantially equal to the intake manifoldair pressure (MAP). For example, at notch eight of some engine systems,the first pressure sensor 232 may measure a pressure of approximately 45psig (˜3 bar).

The turbocharger 200 further includes bearings 208 to support the shaft206, such that the shaft may rotate at a high speed with reducedfriction. The turbocharger may further include a lubrication system toreduce degradation of the bearings and to maintain a temperature of thebearings (e.g., to keep the bearings cool). While the engine is inoperation, a constant flow of engine oil or engine coolant may passthrough the turbocharger, for example. In one example, pressurizedengine oil may enter the turbocharger via an oil inlet (not shown).Excess oil may collect in an oil cavity 212, and the oil leaves theturbocharger 200 through an outlet (not shown) fluidly coupled with theoil cavity 212. As depicted in FIG. 2, an oil cavity pressure sensor 230is positioned in the oil cavity 212 to measure a pressure in the oilcavity. The oil cavity pressure sensor 230 may be in addition to thefirst pressure sensor 232, or it may be alternative thereto. The oilcavity pressure sensor 230 may be a transducer, for example, whichgenerates a signal as a function of the pressure imposed.

As depicted in FIG. 2, the turbocharger 200 further includes twonon-contact seals (e.g., labyrinth seals), a turbine labyrinth seal 216positioned between the oil cavity 212 and the turbine 202 and acompressor labyrinth seal 218 positioned between the oil cavity 212 andthe compressor 204. A labyrinth seal as used herein refers to a type ofmechanical seal that provides a tortuous or serpentine path to helpprevent leakage. (As opposed to, for example, an O-ring or similarcircular seal.) In one embodiment, the labyrinth seal may be composed ofmany grooves or threads that press tightly against another component.Herein, the labyrinth seal is applied to a rotating shaft system, with asmall clearance between tips of the labyrinth threads and the runningsurface. In this way, the labyrinth seal provides non-contact sealingaction by controlling the passage of fluid. The labyrinth seals 216 and218 may thus reduce leakage of the engine oil used to lubricate thebearings 208 to the turbine 202 and the compressor 204, for example, byproviding a contorted, tortuous path. Because the labyrinth seals 216and 218 are non-contact seals, friction around the bearings 208 and theshaft 206 may be reduced, while oil leakage is also reduced. In oneexample, the labyrinth seals 216 and 218 may be spaced a determineddistance from the bearings 208. Suitable determined distances may bedetermined with reference to application specific parameters, such as ina range of less than ˜ 1/4000 of an inch (˜6×10⁻⁴ cm).

The turbocharger 200 further includes a seal cavity 234 that extendsfrom behind the compressor 204 near the compressor labyrinth seal 218 toan area near the turbine labyrinth seal 216. The seal cavity 234 is anair passage in the casing of the turbocharger 200. As shown in FIG. 2,the seal cavity 234 includes an orifice 236. The orifice is configuredto generate a choked air flow. In such a configuration, the chokedairflow may generate a greater pressure difference further downstreamresulting in better detection of differences in pressure between variouslocations in the turbocharger 200. The seal cavity 234 further includesa second pressure sensor 238 to measure a pressure in the seal cavity234. As depicted in FIG. 2, the second pressure sensor 238 is located ata port of the seal cavity 234. The second pressure sensor 238 may be atransducer, for example, which generates a signal as a function of thepressure imposed. The pressure in the seal cavity 234 may be higher thanthe pressure in the oil cavity 212, for example, such that oil may beretained in the oil cavity. As an example, at notch eight of certainengine systems, the pressure sensor 238 may measure a pressure ofapproximately 27 psig (−2 bar).

Each pressure sensor location may have a different pressure. Forexample, the pressure at the diffuser 228 in the compressor casing maybe higher than the pressure in the seal cavity 234, and the pressure inthe seal cavity 234 may be higher than the pressure in the oil cavity212. Further, the differences between each pressure may change withoperating conditions such as turbine or compressor speed, notch settingof the engine, ambient temperature and/or pressure, and the like. Whendegradation of the turbine labyrinth seal 216 and/or the compressorlabyrinth seal 218 occurs due to the shaft 206 rubbing the seals becauseof rotor imbalance or axial shifts, pressure in the seal cavity 234 maydecrease, while the pressure at the diffuser 228 in the compressorcasing remains substantially the same. As such, degradation of thelabyrinth seals 216 and 218 may be diagnosed based on a pressuredifference between a pressure measured in the seal cavity 234 and apressure measured at the diffuser 228 in the compressor casing greaterthan respective threshold differences.

In one embodiment, a system comprises a turbocharger with a compressorand a turbine, a first pressure sensor which generates a first signal,and a second pressure sensor which generates a second signal. The firstpressure sensor is disposed in an oil cavity of the turbocharger, andthe second pressure sensor disposed in a seal cavity of theturbocharger. The system further comprises a controller configured toidentify a first pressure from the first signal and a second pressurefrom the second signal and to identify degradation of the turbochargerif a difference between the first pressure and the second pressure isgreater than a first threshold difference. In embodiments, identifyingdegradation of the turbocharger includes outputting a control signal,e.g., for initiating an alarm or alert or controlling a vehicle system.

In some embodiments, an upgrade kit that may be installed in a railvehicle or other vehicle may include a non-transient computer readablemedium including instructions for determining degradation of aturbocharger based on pressure values measured within the turbocharger,as described above. The upgrade kit may further include a plurality ofpressure sensors or other mechanical elements that may be installed inthe turbocharger system.

FIGS. 3, 4, and 6 show flow charts illustrating exemplary methods whichmay be carried out in a vehicle system which includes a turbochargercoupled to an engine. FIG. 3 shows a method for diagnosing degradationof non-contact seals disposed around the turbocharger shaft based onmeasured pressure differences within the turbocharger. FIG. 4 shows amethod for diagnosing degradation of the turbine or compressor of theturbocharger based on frequency content of a measured pressure withinthe turbocharger. FIG. 6 shows a method for diagnosing degradation ofnon-contact seals disposed around the turbocharger shaft based onmeasured pressures within the turbocharger. The methods described withreference to FIGS. 3, 4, and 6 may be carried out by the same controllerand at the same time, for example. As an example, a second pressure maybe measured to compare with a first pressure, frequency content of thesecond pressure may also be determined, and the first and/or secondpressures may be compared to respective threshold pressures. Further,the methods described with reference to FIGS. 3, 4, and 6 are carriedout while an engine to which the turbocharger is coupled is operating(e.g., while combustion is occurring), and may be carried out while avehicle in which the turbocharger is positioned is travelling.

In one example embodiment, a method comprises determining a firstpressure at a first location in a turbocharger, determining a secondpressure at a second location in a turbocharger, and determiningfrequency content of the second pressure. The method further comprisesdiagnosing a condition of the turbocharger based on a difference betweenthe first pressure and the second pressure and the frequency content ofthe second pressure.

Turning to FIG. 3, a method 300 for diagnosing a condition in aturbocharger, such as the turbocharger 200 described above withreference to FIG. 2, is shown. Specifically, the method includesmeasuring pressure via pressure sensors positioned at various locationswithin the turbocharger and comparing the measured pressure values. Forexample, a first pressure measured at a first location is compared to asecond pressure measured at a second location. Degradation of theturbocharger is determined based on the difference in the measuredpressure values. As described above, the method is carried out while anengine to which the turbocharger is coupled is in operation, and may becarried out while a vehicle, such as a rail vehicle, in which theturbocharger is positioned is travelling. In this manner, pressuredifferences between the various cavities of the turbocharger may begreat enough to measure.

At step 302, system operating conditions are determined. The operatingconditions may include boost pressure, ambient pressure, ambienttemperature, engine notch setting, and the like.

Once the operating conditions are determined, the method proceeds tostep 304 where a first pressure is measured at a first location. Asdescribed above, the turbocharger may have a plurality of pressuresensors positioned at various locations within the turbocharger. Assuch, the first pressure may be measured by a first pressure sensorlocated in the oil cavity, a pressure sensor located at the diffuser inthe compressor casing, or a pressure sensor located in the seal cavity.In other embodiments, the first pressure may be measured at anothersuitable location within the turbocharger.

At step 306, a second pressure is measured at a second location. Thesecond location may be a location other than the first location. Forexample, the first pressure may be measured by the first pressure sensorin the oil cavity and the second pressure may be measured by the secondpressure sensor in the seal cavity. As another example, the firstpressure may be measured by the first pressure sensor at the diffuser inthe compressor casing and the second pressure may be measured by thesecond pressure sensor in the seal cavity. In other embodiments, thesecond pressure may be measured at another suitable location within theturbocharger.

Once the first pressure and the second pressure are determined, it isdetermined if a difference between the first pressure and the secondpressure is greater than a threshold difference at step 308. Theparticular threshold difference against which the first and secondpressures are assessed may depend on the locations in the turbochargerwhere the first and second pressures are sensed, with different sets oflocations having different threshold differences. For example, thethreshold difference between the pressure in the seal cavity and thepressure in the oil cavity (if the first and second pressures aremeasured at these locations) may be a first threshold difference, andthe threshold difference between the pressure in the seal cavity and thepressure at the diffuser in the compressor casing (if the first andsecond pressures are measured at these locations) may be a secondthreshold difference. The first threshold difference may have adifferent value than the second threshold difference, as each of themeasured pressures may have different values under normal operatingconditions. As an example, under normal operating conditions in whichthe turbocharger is healthy (e.g., not degraded), the first pressure inthe oil cavity may have a particular value and the second pressuremeasured in the seal cavity may have a higher value such that the oilcavity retains oil. Further, the pressure measured in the seal cavitymay vary with operating conditions such as engine notch, engine speed,ambient temperature, ambient pressure, engine oil temperature, enginecoolant temperature, fuel injection advance angle, charge air pressure,turbocharger speed, and/or charge air temperature. For example, the sealcavity may have a higher pressure at a higher engine notch (e.g., atnotch eight as compared to notch four). Likewise, the thresholddifference may change based on operating conditions such as compressorspeed, engine load, engine notch, and the like. For example, as thespeed of the compressor decreases, the seal cavity pressure may alsodecrease resulting in a decreased pressure difference between the sealcavity and the oil cavity. As such, a threshold difference between theseal cavity and the oil cavity, for assessing pressures at theselocations in regards to possible turbocharger degradation, may decreasecorrespondingly such that degradation of the turbocharger is not falselyidentified.

As another example, under normal operating conditions in which theturbocharger is healthy, the first pressure at the diffuser in thecompressor casing may have a value similar to the manifold air pressureand the second pressure measured in the seal cavity may have a lowervalue. The pressures measured at the diffuser in the compressor casingand in the seal cavity may vary with operating conditions, such asengine notch setting and turbocharger speed. For example, the pressuremeasured at the diffuser in the seal cavity may increase with enginenotch (e.g., the pressure is higher at notch seven than at notch six).

The difference between the first pressure and the second pressure undervarious operating conditions may be stored in a look-up table, forexample. When the absolute value of the pressure difference between thefirst and second pressure crosses a threshold value, degradation of theturbocharger is indicated at step 310. In one example, when thedifference between the first pressure and the second pressure is greaterthan a threshold value, degradation of a non-contact seal, such as theturbine or compressor labyrinth seals, may be diagnosed. (For effectinga diagnosis of this type, sensors could be placed at various locationswithin the turbocharger, such as the oil cavity, seal cavity, at thediffuser in the compressor casing, or the like.) For example, due torotor imbalance or axial shifts, the rotating shaft of the turbochargermay rub on the non-contact labyrinth seals, thereby generating aclearance around the non-contact labyrinth seals and increasing airflowto the crankcase leading to crankcase overpressure and a decrease inseal cavity pressure. Thus, as the seal cavity pressure decreases, thedifference between the seal cavity pressure and the oil cavity pressurechanges and the difference between the seal cavity pressure and pressureat the diffuser in the compressor casing changes.

For a look-up table, the look-up table would include a list ofdesignated operating conditions (of a class, type, or configuration ofengines, vehicles, or other systems), and for each operating condition,an associated threshold value for a pressure difference, determinedempirically for example. In operation, the current operating mode (ofthe engine or vehicle or other system in question) would becross-referenced to the corresponding operating condition of the table,for retrieving the associated threshold value. The pressure difference(difference between first and second sensed pressures in a turbocharger)would then be compared to the retrieved threshold value, for assessingturbocharger health.

The controller may be configured to notify an operator of the vehicle(or other system) in which the engine is positioned of the diagnosis,for example, by sending a diagnostic code to light a malfunctionindicator lamp (MIL) which is displayed via an operator interface panel,sending a diagnostic code to a central dispatch control center, or thelike. In response receiving the diagnostic signal, turbochargeroperation may be suspended, for example, such that further degradationof the engine system and/or turbocharger system does not occur. Once theengine is shut down, the turbocharger may be removed from the vehicleand repaired or replaced. In other examples, engine operation and/orturbocharger operation may be adjusted to compensate for the degradedturbocharger until the engine is shut down. In still other examples, theengine may be shut down upon receiving the diagnostic code indicatingdegradation of the turbocharger has occurred, such that furtherdegradation of the turbocharger system and/or engine system may bereduced.

On the other hand, if the difference between the first pressure and thesecond pressure is less than the threshold difference, the method movesto step 312 where it is indicated that the turbocharger is not degraded(or, in certain embodiments, no action is taken).

In this manner, a degraded condition of the turbocharger may bediagnosed while the turbocharger is in operation. For example,degradation of the turbocharger due to leaks in one or more non-contactseals such as the compressor and turbine labyrinth seals may beidentified due to a pressure difference between the first and secondpressure that is greater than a threshold difference. When thedifference is not greater than the threshold difference, it may beindicated that an engine crankcase over pressure event may be due to acondition other than a degraded turbocharger, such as degraded pistonrings or some other source.

FIG. 4 is a flow chart illustrating a method 400 for diagnosing acondition of a turbocharger, such as the turbocharger 200 describedabove with reference to FIG. 2, based on frequency content of a pressuresignal. Specifically, the method includes determining frequency contentfrom a pressure measured at a location within the turbocharger. Based onthe frequency content, degradation of the turbine or compressor isidentified. As described above, the method is carried out while anengine to which the turbocharger is coupled, and may be carried outwhile a vehicle, such as a rail vehicle, in which the turbocharger ispositioned is travelling. For example, because the frequency contentwhich is determined via the method is based on rotation of the turbinefan or compressor fan, the turbocharger is supplying boost to the engineduring engine operation.

At step 402, system operating conditions are determined. The operatingconditions may include boost pressure, speed of the turbine and/orcompressor of the turbocharger, ambient pressure, ambient temperature,and the like.

At step 404, pressure is measured at a location within the turbocharger.As described above, pressure sensors may be disposed in a plurality oflocations within the turbocharger, and as such, pressure may be measuredin a seal cavity, in an oil cavity, at a diffuser in the compressorcasing, and/or at another suitable location within the turbocharger.

Once the pressure (or pressures) is measured, frequency content of thepressure signal is determined at step 406. For example, because thedegradation of the turbine or compressor blades may be most obvious inthe seal cavity pressure, frequency content of the pressure measured inthe seal cavity may be determined. The frequency content of the pressureis the relative magnitudes of frequency components of a frequency domainpressure signal and/or is a measured frequency content as created with aband-pass filter. In one example, the frequency content may bedetermined by filtering the signal, sampling the signal, transformingthe signal, and applying a correlation algorithm to the signal.

In one example embodiment, the pressure signal may be filtered by alow-pass filter with a cut-off frequency slightly greater than afirst-order frequency. For example, the cut-off frequency may be ten totwenty percent greater than the first-order frequency. As such, thecut-off frequency may be determined by a speed of the turbine orcompressor. The first-order frequency component may be attributed tospinning of the turbine or compressor fan. For example, in onerevolution of the compressor fan, eight fan blades may pass a particularpoint. Thus, the spinning of the compressor fan may cause a pressurewave inside the crankcase at a frequency corresponding to the number offan blades and the fan revolution frequency.

Further, the pressure may be sampled at a frequency greater than orequal to a Nyquist rate. In one embodiment, the pressure signal may besampled at a frequency greater than twice the first turbine orcompressor order frequency. In one embodiment, the pressure signal maybe sampled at a frequency greater than twice the maximum turbine orcompressor frequency. Thus, by low-pass filtering and sampling at afrequency greater than or equal to the Nyquist rate, the frequencycontent of the pressure may not be aliased. Once the pressure issampled, the pressure may be transformed. For example, the sampledpressure may be transformed to generate a frequency domain pressuresignal. In one example, a fast Fourier transform may be used to generatethe frequency domain pressure signal. Next, a correlation algorithm maybe applied. In one example, a correlation algorithm may be applied tocompare the frequency domain pressure signal, e.g., the frequencycontent of the pressure, to a signature for a condition of theturbocharger. For example, the signature for a healthy turbocharger mayinclude frequency content at the first-order frequency.

At step 408, mean/average values of the frequency are determined. Theaverage value may be used with the frequency content to diagnoseturbocharger degradation. For example, the presence of a pressure pulseabove a specified threshold in both average value and frequency contentmeasured in the oil cavity may indicate bearing and non-contact sealfailure, which may result in charged air flowing to the enginecrankcase, leading to a crankcase overpressure event.

Once the frequency content is determined, it is determined if a fault isdetected, at step 410. As an example, the pressure may also includefrequency content at other harmonics of the first-order frequency, suchas at a second-order frequency (twice the frequency), a third-orderfrequency (three times the frequency), etc. Similarly, the crankcasepressure may include frequency content at frequencies less than thefirst-order frequency, such as at a half-order frequency (half thefrequency). A fault may be indicated by a harmonic of the first-orderfrequency, for example, a half-order frequency greater than a thresholdvalue may indicate a broken fan blade. Thus, if a fault is detected, themethod continues to step 412 where degradation of the turbocharger isindicated. As described above, when degradation is identified, thecontroller may send a diagnostic code to light a malfunction indicatorlamp (MIL) which is displayed via an operator interface panel, send adiagnostic code to a central dispatch control center, or the like.

On the other hand, if a fault is not detected at step 408, the methodmoves to step 412 and it is indicated that the turbocharger is notdegraded (or, in other embodiments, no action is taken).

FIG. 5 shows a graph 500 showing example frequency content of a pressuresignal. The first-order frequency is shown at 502 below a thresholdvalue 504. As described above, the first-order frequency component maybe attributed to rotation of the turbine or compressor fan. If the firstorder frequency is below the threshold value 504, this may indicate abalanced, or healthy, turbine or compressor fan. If the turbine orcompressor is imbalanced, due to a fan blade breaking for example, amagnitude of the first order frequency may increase such that it ishigher than the threshold 504. The threshold value 504 may change basedon various operating conditions, such as fan speed, engine load, enginenotch setting, ambient temperature, ambient pressure, engine oiltemperature, engine coolant temperature, fuel injection advance angle,charge air pressure, turbocharger speed, charge air temperature, and thelike. For example, a higher fan speed (e.g., faster rotation of the fan)may have a first-order frequency with a greater magnitude. As such, thethreshold value 504 may increase with fan speed. In this manner,degradation of the compressor or turbocharger fan may be identified.

Thus, frequency content of the measured pressure signal may bedetermined. By analyzing the frequency content of the pressure signal, acondition such as a degraded compressor or turbine, due to a broken fanblade for example, may be diagnosed. As such, a more specific diagnosisof the turbocharger degradation may be provided.

FIG. 6 shows a method 600 for diagnosing a condition in a turbocharger,such as the turbocharger 200 described above with reference to FIG. 2.Specifically, the method includes measuring pressures using pressuresensors positioned at various locations within the turbocharger, andcomparing the measured pressure value(s) to respective thresholdpressure(s). For example, a first pressure measured at a first locationis compared to a first threshold pressure. Degradation of theturbocharger is determined based on the first pressure falling below thefirst threshold pressure. As described above, the method is carried outwhile an engine to which the turbocharger is coupled is in operation,and (possibly) while a vehicle, such as a rail vehicle, in which theturbocharger is positioned is travelling.

At step 602, operating conditions are determined. The operatingconditions may include boost pressure, ambient pressure, ambienttemperature, engine notch setting, and the like.

At step 604, pressure is measured at a location within the turbocharger.As described above, pressure sensors may be disposed in variouslocations within the turbocharger, such as at a diffuser in thecompressor casing, in a seal cavity, in an oil cavity, or the like. Insome examples, the pressure may be determined at a location such as inan intake manifold of the engine. In some examples, pressure may bemeasured at more than one location. For example, the pressure may bemeasured in the oil cavity and the seal cavity, or the pressure may bemeasured in the oil cavity, and/or the seal cavity.

Once the pressure is measured, it is determined if the measured pressurehas passed a threshold pressure at step 606. For example, if one or bothof the non-contact compressor labyrinth seal and the turbine labyrinthseal are degraded, a pressure in the oil cavity may increase and thepressure may exceed the threshold pressure. As another example, if oneor both of the non-contact seals have degraded, a pressure in the sealcavity may decrease and the pressure may fall below the thresholdpressure. In some examples, pressure may be measured at multiplelocations and compared to respective thresholds. For example, a firstpressure may be measured at a first location in the oil cavity and asecond pressure may be measured in a second location at the diffuser inthe compressor casing. The first pressure is compared to a firstthreshold pressure corresponding to a threshold pressure for the oilcavity, and the second pressure is compared to a second thresholdpressure corresponding to a threshold pressure for the diffuser. If boththe first and second pressures are past their respective thresholds,degradation may be indicated. It should be understood that the thresholdpressure may vary based on engine operating conditions. For example, thethreshold pressure, as well as the measured pressure, may change withengine speed, engine load, ambient temperature, ambient pressure, engineoil temperature, engine coolant temperature, fuel injection advanceangle, charge air pressure, turbocharger speed, charge air temperature,and the like.

If it is determined that the measured pressure has not passed thethreshold pressure, it is indicated that the turbocharger is notdegraded, at step 610. Alternatively, no action may be taken, in certainembodiments. On the other hand, if it is determined that the measuredpressure has passed the threshold pressure, it is indicated that theturbocharger is degraded, at step 608. As described above, whendegradation is identified, the controller may send a diagnostic code tolight a malfunction indicator lamp (MIL) which is displayed via anoperator interface panel, send a diagnostic code to a central dispatchcontrol center, or the like.

In this way, a degraded condition of the turbocharger may be diagnosedwhile the turbocharger is in operation. For example, degradation of theturbocharger due to leaks in one or more non-contact seals such as thecompressor and turbine labyrinth seals may be identified when one ormore measured pressures within the turbocharger pass respectivethreshold pressures. When the measured pressure has not passed thethreshold pressure, it may be indicated that an engine crankcase overpressure event may be due to a condition other than a degradedturbocharger, such as degraded piston rings or some other source.

In some embodiments, degradation of the turbocharger may be based on ameasured pressure difference within the turbocharger, frequency contentof one of the pressure signals, and comparison of measured pressure witha threshold pressure. As an example, the frequency content may bedetermined only if the pressure difference is greater than a thresholddifference, and the pressure difference may be determined only if themeasured pressure has passed a threshold pressure.

In embodiments, parameters (e.g., pressure threshold values) forassessing turbocharger health or condition are determined empirically asa function of engine/system operating mode. For a given engine/system,pressures in a turbocharger of the system are measured for variousoperating modes, when the engine/system is known to be workingoptimally. For example, the engine/system may be a test model, a newmodel, a recently serviced model, etc. (Locations where the pressuresmay be measured are as described in the other sections in the presentdescription.) The pressure values are then stored and used for assessingturbocharger health in engine/systems of the same or similar type. Inanother embodiment, pressure values are measured in several units of thesame type of engine/system (known to be working optimally) and averagedor otherwise processed for determining a set of composite values to beused in assessing engine/systems of the same or similar type. In anotherembodiment, pressure values are measured in an engine/system that hasbeen deployed in the field for normal and ongoing use, but at a timewhen the engine/system is new and/or otherwise considered to be workingoptimally. The pressure values are stored and then referenced duringongoing use of the engine/system, for future assessments of turbochargerhealth. In another version of such an embodiment, initially-sensedpressure values (in a new, deployed engine/system) are only used forfuture assessment if they fall within an error threshold of test valuesfor the same or similar type of engine/system. Thus, if theinitially-sensed values are (relatively) far away from expected values,based on a designated error threshold or otherwise, an alert or alarm isgenerated for informing an operator that something may be amiss, or asimilar remedial action is taken. “Engine/system” means an engine,engine system, vehicle or other system having an engine system, or thelike.

Another embodiment relates to a method comprising a step of determininga first pressure at a first location within a turbocharger, and a stepof determining a second pressure at a second location within theturbocharger. The method further comprises a step of outputting acontrol signal, indicative of or responsive to a condition of theturbocharger, based on the first pressure and the second pressure.

In another embodiment of a method, the method comprises determining afirst pressure at a first location in a turbocharger, determining asecond pressure at a second location in a turbocharger, and determiningfrequency content of the first second pressure. The method furthercomprises outputting a control signal, indicative of or responsive to acondition of the turbocharger, based on the first pressure, the secondpressure, and the frequency content of the second pressure.

Another embodiment relates to a system including a turbocharger with acompressor and a turbine. The turbocharger is coupled to an engine in avehicle. The system further includes a first pressure sensor, a secondpressure sensor, and a controller. The first pressure sensor is disposedin an oil cavity of the turbocharger and configured to generate a firstsignal. The second pressure sensor is disposed in a seal cavity of theturbocharger and configured to generate a second signal. The controlleris configured to identify a first pressure from the first signal and asecond pressure from the second signal, and to determine a state of theturbocharger based on the first and second pressures. For example, thecontroller may be configured to determine a health state of theturbocharger based on the first and second pressures. The health stateof the turbocharger may reflect, for example, intervals required betweenmaintenance operations and/or replacement. Thus, if the health state ofthe turbocharger degrades, maintenance operations may be required atmore frequent intervals, while if the health state of the turbochargerimproves, maintenance operations may be required at less frequentintervals. As another example, the controller may be configured todetermine whether the turbocharger has degraded (e.g., to the pointwhere servicing is required) based on a difference between the firstpressure and the second pressure, such as the difference being greaterthan a designated threshold difference.

Another embodiment relates to a system comprising a control moduleconfigured to receive a first pressure signal from a first pressuresensor disposed in a first location of a turbocharger. The controlmodule is further configured to receive a second pressure signal from asecond pressure sensor in a second location of the turbocharger. (Thefirst and second locations may be as described elsewhere in the presentdescription.) The control module is further configured to output acontrol signal based on the first pressure signal and the secondpressure signal. For example, the control module may be configured toassess possible degradation of the turbocharger based on the first andsecond pressure signals, and to output the control signal responsive todetermining degradation of the turbocharger. The control signal may beformatted or configured to control a system (e.g., operator interface,alarm) for indicating the degradation, or the control signal may be usedto control a vehicle traction system to account for the degradation. Thecontrol module may be a hardware and/or software module, meaning it maycomprise: interconnected electronic components configured to carry outone or more designated functions (e.g., receive input signals, andgenerate output/control signals based on the input signals); and/orsoftware, meaning one or more sets of electronically readableinstructions, stored in non-transitory media/medium, that when read andexecuted by an electronic device (group of interconnected electroniccomponents) cause the electronic device to perform one or more functionsaccording to the contents of the instructions.

In another embodiment, the control module is configured to determine apressure difference based on the first pressure signal and the secondpressure signal, and to determine whether the pressure difference meetsone or more designated criteria. If the pressure difference meets theone or more designated criteria, the control module is configured tooutput a control signal indicative of, or relating to, a degradedturbocharger condition. The one or more designated criteria arepre-determined as a function of the locations of where the pressures aremeasured, and are indicative of a degraded condition of theturbocharger. For example, a healthy turbocharger may normally have afirst pressure difference between two points, as a function of operatingmode. The one or more criteria comprise deviating from the firstpressure difference (either smaller or larger pressure difference) bymore than a threshold. As another example, one or more criteria maycomprise deviating from the first pressure difference by more than athreshold that reflects only a larger pressure difference, or only asmaller pressure difference. That is, if the pressure difference isnormally “X,” in one embodiment the criteria are met only if X isexceeded by a threshold, and in another embodiment, the criteria are metonly if the sensed pressure difference is lower than X by a threshold.The criteria selected will depend on the particular turbocharger andlocations of where pressure is measured.

In another embodiment, the control module is configured to perform afrequency analysis of one or both of the first and second pressuresignals, and to output the control signal based (at least in part) onthe frequency analysis.

In one embodiment, as described below with reference to FIGS. 7-9, thecontroller 148 (described above with reference to FIG. 1) may beconfigured to receive signals indicative of turbocharger oil pressurefrom an oil pressure sensor, such as a transducer, associated with aturbocharger and determine bearing failure via one or more of frequencycontent and baseline content of the pressure signal. As described abovewith reference to FIG. 4, bearing and/or non-contact seal degradationmay be determined based on frequency content of a pressure signal, suchas various harmonics of the pressure signal, measured at variouslocations within the turbocharger. As will be described in greaterdetail below, another method for identifying degradation of turbochargerbearings based on frequency content may be based on a high frequencycomponent of the pressure signal and/or a baseline component of thepressure signal, where the pressure is measured in a pressurized oilsupply of the turbocharger.

FIG. 7 shows a view of an exemplary embodiment of a turbocharger 700that may be coupled to an engine, such as turbocharger 120 describedabove with reference to FIG. 1. The view shown in FIG. 7 is across-sectional view of a portion of the turbocharger 700. In oneexample, turbocharger 700 may be bolted to the engine. In anotherexample, the turbocharger 700 may be coupled between the exhaust passageand the intake passage of the engine. In other examples, theturbocharger may be coupled to the engine by another suitable manner.

The turbocharger 700 includes a turbine 702 and a compressor 2704.Exhaust gases from the engine pass through the turbine 702, and energyfrom the exhaust gases is converted into rotational kinetic energy torotate a shaft 206 which, in turn, drives the compressor 704. Ambientintake air is compressed (e.g., pressure of the air is increased) as itis drawn through the rotating compressor 704 such that a greater mass ofair may be delivered to the cylinders of the engine.

In some embodiments, the turbine 702 and the compressor 704 may haveseparate casings which are bolted together, for example, such that asingle unit (e.g., turbocharger 700) is formed. As an example, theturbine may have a casing made of cast iron and the compressor may havea casing made of an aluminum alloy. In other examples, casings of theturbine and the compressor may be made of the same material. It shouldbe understood the turbine casing and the compressor casing may be madeof any suitable materials.

The turbocharger 700 further includes journal bearings 708, 710 tosupport the shaft 706, such that the shaft may rotate at a high speedwith reduced friction. A compressor bearing is indicated at 708, and aturbine bearing is indicated at 710. The turbocharger may furtherinclude a lubrication system to reduce degradation of the bearings andto maintain a temperature of the bearings (e.g., to keep the bearingscool). While the engine is in operation, a constant flow of engine oilor engine coolant may pass through the turbocharger, for example. In oneexample, pressurized engine oil may enter the turbocharger via an oilinlet 712. An oil pressure sensor 714 (e.g., transducer) is operablydisposed with respect to the oil inlet. For example, the oil pressuresensor 714 may be disposed within a pressurized oil supply. Inoperation, the oil pressure sensor 714 generates a signal 716 indicativeof the pressure of oil associated with the journal bearings. The signal716 may be supplied to the controller 148, for example.

During operation of the turbocharger, oil is supplied to theturbocharger from the engine oil supply, by way of an oil pump or thelike. After engine startup, the supply pressure reaches a steady statevalue 800, as shown in FIG. 8. The pressure of oil supplied to theturbocharger will be somewhat lower, but also reaches a baselinepressure 802 after engine startup. (“Baseline” refers to a steady statepressure, e.g., having only relatively low frequency variations, and/ora post engine startup turbocharger oil pressure associated with a newturbocharger or a turbocharger that is otherwise known to be operatingnominally.)

In embodiments of the invention, the high frequency content of the oilsupply pressure is monitored to predict destructive shaft motion andprogressive bearing failure. For such a purpose, the baselineturbocharger oil pressure may also be monitored. When the shaft isbalanced and the bearing is operating normally, the oil pressure in theturbocharger will be steady and predictable. When the shaft isoscillating due to unbalance or bearing wear, higher frequency pressuresignals will be detected by the pressure transducer. Together, thebaseline pressure and high frequency signals can predict the health ofthe shaft and bearing. This health status can inform the operator of theturbocharger's safe life expectancy for taking appropriate action.

To explain further, when a properly designed turbocharger journalbearing is operating in a normal manner, the unbalance and bearing whirlforces do not exceed the gravity load on the bearings. Due to the highspeed (rpm) and relatively light loads associated with turbochargershafts, the bearings are designed to support the shaft on discreteareas, called pads. The shaft runs stably in the pads. This stable shaftoperation does not transmit any high frequency pressure waves back tothe pressure transducer. When the rotor shaft unbalance forces are highenough to force the shaft out of the stable position, the shaft willwhirl in the bearing, causing rapid changes in the bearing clearance.The shaft will impact the bearing, causing high frequency pressurewaves. The pressure waves from these destructive motions will betransmitted back up the oil supply drilling and can be detected by theoil pressure sensor. If these destructive motions are allowed tocontinue for some time, wear and deformation may occur in the bearingthat may result in excessive bearing clearance. The increased bearingclearance may reduce the baseline pressure sensed by the oil pressuretransducer. The increase in bearing clearance will make the shaft motioneven greater, resulting in bearing failure.

In an embodiment, with reference to FIGS. 7 and 8, a method comprisesreceiving a signal 716 indicative of a monitored pressure of apressurized oil supply of a turbocharger 700 or other turbomachine. Themethod further comprises determining whether a high frequency component804 of the signal meets one or more designated criteria. If the highfrequency component of the pressure meets the one or more designatedcriteria, a first control signal 806 is generated. For example, thecontrol signal may initiate an operator alert relating to a predicatedhealth (or other operational state) of the turbocharger.

In another embodiment, the method further comprises monitoring thebaseline component 802 of the signal. The method further comprisesgenerating a second control signal 808 if a magnitude of change in thebaseline component is more than a threshold amount. In one particularexample, the method may determine whether the magnitude of the change isgreater than a threshold when trending downward in generating the secondcontrol signal, whereas in till another example, the method maydetermine whether the magnitude of the change is greater than thethreshold when trending upward when generating the second controlsignal.

In another embodiment, a method comprises receiving a signal 716indicative of a monitored pressure of a pressurized oil supply of aturbocharger 700 or other turbomachine. The method further comprisesconducting a first assessment of a high frequency component 804 of thesignal, and conducting a second assessment of a baseline component 802of the signal. Based on the first and second assessments, a controlsignal indicative of a predicted operational state of the turbochargeris generated. The first assessment may comprise determining if the highfrequency component of the signal meets one or more designated criteria,and the second assessment may comprise determining if a magnitude ofchange in the baseline component of the signal is more than a thresholdamount (and, trending downward or upward).

Determining whether the magnitude of change in the baseline component802 is more than the threshold amount (that is, whether the baselinecomponent is trending downward or upward) may include: storing data ofthe baseline component over time; and comparing earlier values of thebaseline component to a current value (or plural subsequent values thatwere recorded after the earlier values). In one example, if the currentvalue (or subsequent values) is lower than the earlier values (e.g.,lower by at least a threshold amount), then the baseline component maybe determined to be trending downwards. In another example, if thecurrent value (or subsequent values) is higher than the earlier values(e.g., higher by at least a threshold amount), then the baselinecomponent may be determined to be trending upwards. In either case, amagnitude of change in the baseline component may be higher than thethreshold amount.

Determining if the high frequency component of the signal meets one ormore designated criteria may comprise processing the signal using asignal processor or the like. In one embodiment, the criterion comprisesthere being any high frequency component. That is, if there is a highfrequency component, then the criterion is deemed as having been met.Other criteria may relate to the frequency and magnitude of the highfrequency component. “High” frequency component means: a higherfrequency than the baseline component by at least a threshold; and/or afrequency range empirically determined to be indicative of bearing wear,based on experimental analysis; and/or a frequency commensurate with thespeed (rpm) of the turbocharger shaft. The signal 716 may be assessed,in regards to its high frequency component (if any), using standardsignal processing techniques.

FIG. 9 shows a flow chart illustrating a method 900 for diagnosing aturbocharger, such as the turbocharger 700 described above withreference to FIG. 7. Specifically, the method determines a predictedhealth of the bearings and shaft of the turbocharger based on a pressuremeasurement in an oil supply cavity of the turbocharger. The predictedhealth state of the turbocharger may also include a safe life expectancyof the turbocharger. As such, this may reflect, for example, intervalsrequired between turbocharger maintenance operations. Thus, if thepredicted health state of the turbocharger degrades (that is, the safelife expectancy reduces), maintenance operations will be required atmore frequent intervals. In comparison, if the predicted health state ofthe turbocharger improves (that is, the safe life expectancy increases),maintenance operations will be required at less frequent intervals.

At step 902 of the method, system operating conditions are determined.The operating conditions may include boost pressure, turbine speed,ambient pressure, ambient temperature, engine notch setting, and thelike.

Once the operating conditions are determined, the method proceeds tostep 904 where the pressure is measured in the oil supply. For example,the pressure may be monitored by a pressure sensor, such as a pressuretransducer or other suitable pressure measuring device.

At step 906, a first assessment is conducted to determine a highfrequency component of the pressure signal. As described above, the highfrequency component of the pressure signal may be a higher frequencythan a baseline component of the signal by at least a threshold. Inother examples, the high frequency component may be a frequency rangeempirically determined to be indicative of bearing wear, based onexperimental analysis. As another example, the high frequency componentmay be a frequency commensurate with the speed of the turbochargershaft. For example, the high frequency component may be a harmonic ofthe turbine speed.

Once the first assessment is conducted, the method continues to step 908where it is determined if the high-frequency component meets one or moredesignated criteria. As one example, the designated criteria may includethe high frequency component of the signal meeting or exceeding athreshold frequency.

If it is determined that the high frequency signal meets the designatedcriteria, the method moves to step 916 where a first control signal isgenerated. The first control signal may indicate an operator alertrelating to a predicted health of the turbocharger. For example, thecontrol signal may be formatted such that a system, responsive to thecontrol signal, generates an operator alert. As an example, thepredicted health may include destructive turbocharger shaft motion andprogressive bearing failure. As such, the first control signal may alsobe formatted to indicate degradation of the turbocharger.

On the other hand, if it is determined that the high frequency componenthas not met the designated criteria, the method proceeds to step 910where a second assessment is conducted to determine a baseline componentof the pressure signal. As described above, the baseline component maybe a steady state pressure which has only relatively low frequencyvariations. In one example, the baseline component may be a post enginestartup turbocharger oil pressure associated with a new turbocharger ora turbocharger that is otherwise known to be operating nominally. In oneexample, the baseline component of the pressure signal may be storedover time. In such an example, the a current value baseline componentmay be compared to the stored data

As such, once the second assessment is conducted, the method proceeds tostep 912 where it is determined if a magnitude of change in the baselinecomponent of the pressure signal is more than a threshold amount. Thatis, a magnitude of shift from, or change in, baseline pressure pulse ofthe lube oil circuit may be determined. As such, the change may includean increase or decrease in the baseline component of the pressuresignal. In one example, the baseline component may be decreasing and itmay be determined that the baseline component is trending downward ifthe current value of the baseline component is less than the stored databy at least the threshold amount. As an example, the signature of thebaseline component will trend downward once the bearing clearanceincreases. In an alternate example, the baseline component may beincreasing and it may be determined that the baseline component istrending upward if the current value of the baseline component is morethan the stored data by at least the threshold amount. As an example, ifthe overall dynamic response of the system is seen once per revolution(due to imbalance), the signature of the baseline component may trendupward. If it is determined that the baseline component is not changingby more than the threshold amount (that is, not trending downward orupward), the method moves to step 918 and current system operation iscontinued. On the other hand, if it is determined that the magnitude ofchange in the baseline component is more than the threshold amount(e.g., the baseline component is trending downward or trending upward),the method continues to step 914 where a second control signal isgenerated. Similar to the first control signal, the second controlsignal may be indicative of a predicted operational state of theturbocharger. For example, the second control signal may indicatedegradation of the turbocharger, such as destructive turbocharger shaftmotion and progressive bearing failure. As another example, the signalmay indicate that the predicted health of the turbocharger is degradedand/or that the safe life expectancy of the turbocharger has reduced. Byproviding an indication of the turbocharger's predicted health and safelife expectancy, maintenance operations may be appropriately and timelyscheduled.

Due to destructive turbocharger shaft motion resulting from bearingfailure, the high frequency component of the signal may detected or thehigh frequency component may be greater than a threshold frequency.Further, the baseline component of the pressure signal may trenddownward due to bearing failure. Thus, by monitoring one or both of thehigh frequency and baseline components of the pressure in a pressurizedoil supply of the turbocharger, degradation of the turbocharger may bediagnosed. In this way, appropriate actions may be taken to adjust theoperation of the turbocharger and/or provide service to the turbochargerto prevent an unexpected failure, for example.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Moreover, unlessexplicitly stated to the contrary, embodiments “comprising,”“including,” or “having” an element or a plurality of elements having aparticular property may include additional such elements not having thatproperty. The terms “including” and “in which” are used as theplain-language equivalents of the respective terms “comprising” and“wherein.” Moreover, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements or a particular positional order on their objects.

This written description uses examples to disclose the invention,including the best mode, and also to enable a person of ordinary skillin the relevant art to practice the invention, including making andusing any devices or systems and performing any incorporated methods.The patentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those of ordinary skill in the art.Such other examples are intended to be within the scope of the claims ifthey have structural elements that do not differ from the literallanguage of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

1. A method, comprising: receiving a signal indicative of a monitoredpressure of a pressurized oil supply of a turbocharger or otherturbomachine; determining whether a high frequency component of thesignal meets one or more designated criteria; and, if the high frequencycomponent of the pressure meets the one or more designated criteria,generating a first control signal.
 2. The method of claim 1, wherein thecontrol signal indicates an operator alert relating to a predictedhealth of the turbocharger.
 3. The method of claim 2, wherein thepredicted health includes destructive turbocharger shaft motion andprogressive bearing failure.
 4. The method of claim 2, wherein thepredicted health includes a safe life expectancy of the turbocharger. 5.The method of claim 1, further comprising: monitoring a baselinecomponent of the signal; and generating a second control signal if amagnitude of change in the baseline component is more than a thresholdamount.
 6. The method of claim 5, wherein the baseline component of thesignal is a steady state pressure of the pressurized oil supply.
 7. Themethod of claim 5, wherein the second control signal indicatesdegradation of the turbocharger.
 8. The method of claim 1, wherein thehigh frequency component includes frequencies in a range indicative ofbearing wear.
 9. A method, comprising: receiving a signal indicative ofa monitored pressure of a pressurized oil supply of a turbocharger orother turbomachine; conducting a first assessment of a high frequencycomponent of the signal; conducting a second assessment of a baselinecomponent of the signal; and based on the first and second assessments,generating a control signal indicative of a predicted operational stateof the turbocharger.
 10. The method of claim 9, wherein the firstassessment comprises determining if the high frequency component of thesignal meets one or more designated criteria, and the second assessmentcomprises determining if a magnitude of change in the baseline componentof the signal is more than a threshold amount.
 11. The method of claim10, further comprising indicating degradation of the turbocharger whenthe magnitude of change in the baseline component of the signalincreases more than the threshold amount.
 12. The method of claim 10,wherein the designated criteria includes the high frequency component ofthe signal greater than a threshold frequency.
 13. The method of claim12, further comprising indicating degradation of the turbocharger whenthe high frequency component of the signal is greater than the thresholdfrequency.
 14. The method of claim 9, further comprising storing data ofthe baseline component of the signal over time, and wherein conductingthe second assessment including comparing a current value of thebaseline component to the stored data.
 15. The method of claim 9,wherein the high frequency component has a higher frequency than thebaseline by at least a threshold.
 16. A system, comprising: aturbocharger with a compressor and a turbine, the turbocharger coupledto an engine in a vehicle; a pressure sensor configured to generate asignal indicative of a monitored pressure which includes a frequencycomponent and a baseline component, the pressure sensor disposed in apressurized oil supply of the turbocharger; and a control moduleconfigured to receive the signal from the pressure sensor, conduct afirst assessment of the frequency component, conduct a second assessmentof the baseline component, and, based on the first and secondassessments, output a control signal.
 17. The system of claim 16,wherein the control signal is indicative of a predicted operationalstate of the turbocharger.
 18. The system of claim 17, wherein theturbine and the compressor are coupled via a shaft, and wherein thepredicted operational state includes destructive turbocharger shaftmotion.
 19. The system of claim 16, wherein the control module isfurther configured to store data of the baseline component of the signalover time.
 20. The system of claim 19, wherein the control module isfurther configured to compare a current value of the baseline componentto the stored data during the second assessment and to indicatedegradation of the turbocharger when the current value is less than thestored data by at least a threshold.